Most types of crimp-on terminals (or lugs) are attached to wires to allow the wires to be easily connected to screw terminals and fast-on or quick-disconnect terminals. Crimp-on terminals are attached by inserting the stripped end of a stranded wire into the tubular portion of the terminal. The tubular portion of the terminal is then compressed or crimped tightly around the wire by squeezing it with a crimping tool.
Typically, nylon terminals are made up of three components; a connector with integral barrel (ring, fork, etc.), a thin sleeve, and a plastic insulator. The connector and terminal barrel are formed from a sheet metal stamping defining a substantially flat connector portion with either an aperture or fork at the end and a rectangular sleeve or barrel forming portion. After stamping, the rectangular portion is rolled or folded about a mandrel into a tube (referred to herein as “the terminal barrel”) with the side edges abutting each other to form a seam. A thin metal sleeve is snugly fitted over the rolled end and extends past the wire entry barrel end. The sleeve's primary function is to provide strain relief around the wire insulation when it is crimped. Finally, a nylon insulator is fitted over the metal sleeve. Nylon material has memory effect, i.e., it has a tendency to return back to its original processed shape after nylon insulator is crimped. Because of this memory effect, a crimped nylon insulator performs poorly as a strain relief.
Once assembled, a portion at the wire-receiving end of the insulated terminal (at the end opposing the connector) is flared outwardly to increase the inner diameter (“ID”), while the ID of the remaining portion remains unchanged. A conductor with the insulation stripped from the end is inserted into the terminal barrel. The stripped portion of the conductor is received by the unflared portion of the terminal barrel and the insulated portion of the conductor is received by the flared portion. Both the flared and unflared portions of the terminal barrel are then crimped to provide a mechanical strain relief and an electrical connection. When the flared portion of the terminal barrel is crimped, the sleeve forms around the insulation of the conductor to provide strain relief. This construction method is used specifically for nylon insulated terminals, which do not retain their crimped shape well and tend to separate from the insulation of the conductor if a sleeve is not included. Without a sleeve, a crimped nylon insulator provides little or no strain relief. In contrast, vinyl insulated terminals retain their crimped shape and do not require a sleeve to provide good strain relief.
However, vinyl insulators cannot be used in many applications that require terminals rated for high temperatures, increased chemical resistance, impact resistance and/or abrasion resistance. Moreover, the construction method used for nylon insulators requires an additional part (the sleeve) and is, therefore, costly to produce and assemble. Accordingly, there is a need for a high temperature plastic or nylon insulated terminal that is less costly to manufacture and easier to fabricate.